Two types of typical steppe ecosystems in Mongolia (dry steppe and mountain steppe) with two treatments (enclosure and grazing) were studied to analyze the vegetation cover from 2013 to 2018. The plant species of the community were divided into five functional groups: forbs, artemisia, legumes, grasses and sedges. The Gordon stability index was used to evaluate the effect of enclosure on the community stability. Here are the results. 1) Enclosure significantly increased the coverage of forbs in the dry steppe, while reduced the coverage of artemisia and gramineous groups. The effects had no obvious variations among years. For the mountain steppe, enclosure slightly affected the coverage of different functional groups. 2) Enclosure increased the stability of the dry steppe while little influenced the stability of the mountain steppe. 3) The Gordon stability index had a significantly positive relation with the cover ratio of dominant species to the communities. The ratio in the dry steppe was higher than that in the mountain steppe, leading to a higher community stability of the dry steppe. Before the enclosure management in grasslands, we should fully consider local environmental conditions and the potential impact of enclosure on the plant community and the ecosystem. At the same time, grazing rest, rotational grazing, seasonal grazing and other measures should be supplemented to improve the use value of grassland ecosystem services.

基于蒙古国两种典型草地生态系统类型(荒漠草原和高山草原), 采取围封和放牧两种处理方式, 对2013—2018年这两种草地类型的群落盖度进行系统分析。按植物分类学法, 将群落内的所有物种划分为五大功能群——杂草类、蒿类、豆科、禾本科和莎草科, 采用Gordon稳定性方法评估围封对群落稳定性的影响。结果表明: 1) 围封显著增加荒漠草原杂草类植物覆盖度, 减少蒿类和禾本科植物覆盖度, 年际间无明显的变化规律, 而对于高山草原, 围封对不同功能群盖度无显著影响; 2) 围封增加荒漠草原的群落稳定性, 而对高山草原无明显影响; 3) 群落稳定性与优势种盖度占群落的比例呈显著的正相关关系, 荒漠草原的优势种占比高于高山草原, 导致荒漠草原的群落稳定性更好。根据上述结果, 建议在对草地进行围封管理前, 应充分考虑当地的环境条件及围封对植物群落及生态系统的潜在影响, 同时辅以休牧、轮牧或季节性放牧等措施, 才能真正提高草原生态系统服务的使用价值。